Various types of surgical procedures are currently performed to investigate, diagnose, and treat diseases involving a tissue or organs located in a patient's thoracic cavity (e.g., the heart, lungs, and the like).
Using current techniques, many of those procedures typically require a partial or median sternotomy to gain access into the patient's thoracic cavity. A partial or median sternotomy is a procedure by which a saw or other appropriate cutting instrument is used to make a midline, longitudinal incision along a portion or the entire axial length of the patient's sternum, allowing two opposing sternal halves to be separated laterally. A large opening into the thoracic cavity is thus created, through which a surgeon may directly visualize and operate upon the heart and other thoracic organs or tissues.
Following the surgical procedure within the thoracic cavity, the two severed or separated sternal halves must be reapproximated (closed). Traditionally, the sternal halves have been reapproximated with stainless steel wires which are wrapped around or through the sternal halves so as to exert medial compression thereon and twisted together to approximate the sternum. There are inventions disclosed and claimed in Pasque, Michael U.S. Pat. No. 5,423,821 and WO9641581A1, Monassevith, Leonid U.S. Pat. No. 6,171,320 and IL 119911.
Pasque discloses a device and method for closing the sternum using selected plastics or nylon fibers or other strand expandable materials for suturing. A fastener device is also disclosed.
Monassevitch discloses a surgical clip including three lengths of wire integrally formed of a shape memory alloy, two of which form closed geometrical shapes similar in configuration and magnitude to each other, and third connects the first two.
Other methods of sternum repair include the use of band or strap assemblies. Among them are inventions disclosed and claimed in Green, David et al., U.S. Pat. No. 5,417,698 and EP 592960A2; Burgess, Frank et al., U.S. Pat. No. 4,944,753; Golds, Ellen et al., U.S. Pat. Nos. 5,356,412; 5,356,417; EP 596277A1 and EP 597258A1; Sutherland, Lloyd et al., U.S. Pat. No. 4,730,615; Johnson, Greg et al., U.S. Pat. Nos. 6,045,572; 6,080,185; PCT/US99/24164 and Barry, Joseph U.S. Pat. No. 4,583,541.
Such assemblies typically include a locking mechanism, which secures a band or strap in a closed looped configuration about the sternum positions.
For example, Green, David et al., U.S. Pat. No. 5,417,698 and EP 592960A2 disclose an instrument for tightening wound closure elements around human sternum. The instrument includes two handles pivotally attached to one another and movable between an open and closed position. A retaining system is also provided to tighten wound closure material.
Burgess, Frank et al. in U.S. Pat. No. 4,944,753 disclose a method and device for producing an artificial retro-sternal tunnel or space at the conclusion of a sternotomy, and an implantable elongate member for closure of the longitudinally severed sternum.
Golds, Ellen et al. in U.S. Pat. Nos. 5,356,412; 5,356,417; EP 596277A1 and EP 597258A1 disclose a strap assembly to be looped about split portions of sternum including a flexible elongated member and a buckle member with a clamp element rotatably mounted within buckle member from a non-strap securing position to the strap securing position in response to tensional forces exerted on the strap during tensioning thereof about the tissue portion.
Sutherland, Lloyd et al. in U.S. Pat. No. 4,730,615 disclose a sternum closure device made of biocompatible metal coated with a biocompatible polymer and comprising a head portion, tail portion and flexible spine portion. The head portion includes a locking tang to prevent backward movement of the spine portion once it is received and engaged in the head portion.
Johnson, Greg et al. in U.S. Pat. Nos. 6,045,572; 6,080,185 and PCT/US99/24164 disclose a system for closing together two sides of sternum, including a first and second grommets adapted to be disposed on two sides of the sternum, a wire suture, a mechanism for placing a grommet into the sternum and a placement tool. Besides, they disclose a method of threading a wire suture through a hole in a sternum and a method of bringing together two sides of a sternum.
Finally, Barry, Joseph in U.S. Pat. No. 4,583,541 discloses a sternum closure device having an elongated strap-like member provided with a flat back surface which flatly overlies the anterior surface of a severed or separated sternum. The forward surface of the member is convex and longitudinally grooved for nesting the tied or twisted end portions of suture wires extending across the posterior of the sternum and projecting forwardly through cooperating pairs of holes formed in the member on opposing sides of the groove.
While utilization of steel wires and strap assemblies have been widely accepted for sternum repair, these devices present a number of disadvantages. Steel wires can and do break, and provide insufficient (non-uniform) clamping force resulting in sternal nonunion. Steel wires are difficult to maneuver and place around the sternum. The cut ends of the steel wires are also sharp and can pierce through the surgeon's gloves or fingers. In addition, the small diameter of the steel wires can cause the wires to migrate into or through the tissue surrounding the sternum region or into the sternal bone itself over time. This can lead to significant patient pain and discomfort in addition to slowing the postoperative recovery and increasing the risk of sternal infection. Moreover, the strap mechanisms of band assemblies are often relatively structurally complex and are difficult to precisely apply about the sternum. There are also healing problems associated with the use of steel wires and band assemblies due to improper forces exerted by these devices which can cause unwanted bone movements leading to raking and rubbing of surrounding tissue or bone.
Several other techniques of sternal reapproximation have been proposed both for primary closure following a median sternotomy and for reclosure following post-operative emergency surgical procedures. One such sternal closure technique and kit for performing same is described in Zurbrugg, Heinz, U.S. Pat. No. 6,030,410. According to this method, staples are applied to the sternal halves to reinforce the bone adjacent to the suture outlets so as to prevent the suture from cutting into the bone. As each suture loop is tightened to adapt the sternum, the suture loop abuts the staples adjacent the suture outlets. A sterile surgical staple gun is employed to install the staples in the sternal halves.
This method and device and other similar to them, are not optimal, however, because they require direct fixation of the wire to the bone with staples. This makes difficult reentry into the thoracic cavity.
Gabbay, Slomo in U.S. Pat. No. 4,792,248 describes a sternum closure device used for holding together the halves of a split sternum. The device described therein is composed of two plates, one anterior and one posterior to the sternum, that are fixed to each other and to the sternum by means of threaded rods into internally threaded posts positioned in predrilled holes through the bone on either side of the sternotomy.
There are also known methods and apparatus for stapling together severed sternum, including a staple applying tool adapted to drive the staples into or around the sternum halves and lock together these sternum halves. Among them there are U.S. Pat. No. 5,163,598 by Peters, Rudolf et al. and U.S. Pat. No. 4,122,989 by Kapitanov, Nikolai et al. As disclose Peters, Rudolf et al., the sternum stapling apparatus includes a distal shoe with staple forming anvil, a piston within caliper assembly, a staple cartridge and the adjusting tool including a pair of jaws, one having a fulcrum lug and the other having two spaced lugs, whereby the staple may be bent by closure of the lugs together to decrease the linear spacing of the staple legs and increase the abutting force of the bone tissue portions. Kapitanov, Nikolai et al. disclose a surgical instrument for suturing sternal fragments with metal staples including an anvil unit which has two elongated jaws aligned with each other and having inner surfaces facing each other and formed with longitudinal guiding grooves for a staple. The front ends of the jaws carry anvils for bending the tips of the staples. In similar apparatus there may be used special compression bone clips and staples such as described by Wevers, Henk et al. in U.S. Pat. No. 4,444,181 and Murray, William in U.S. Pat. No. 3,960,147.
This device, and others similar to it, are not optimal, however, because they make reentry into the thoracic cavity through the sternotomy extremely difficult if a medical emergency arises during the surgical procedure or post-operative requiring relatively quick access to the organs and/or tissues within the patient's thoracic cavity.